add new howto file

README.md

@@ -61,10 +61,11 @@ $ sudo pacman -Syu mpv anki curl xclip --needed
 ## Prerequisites
 
 * A guide on how to set up Anki can be found [on our site](https://tatsumoto.neocities.org/blog/setting-up-anki.html).
-  Note that it is not recommended to use FlatPak or similar containers.
 * If you're on a [Windows](https://www.fsf.org/windows) or a [Windows-like](https://reactos.org/) machine,
   a mpv build by `shinchiro` is recommended.
 * **macOS** users are advised to use [homebrew](https://brew.sh/) or manually add `mpv` to `PATH`.
+* Note that it is not recommended to use FlatPak or similar containers.
+  If you still want to, [read this](howto/flatpak.md).
 * Make sure that your build of mpv supports encoding of audio and images.
   This shell command can be used to test it.
 
@@ -74,8 +75,8 @@ $ sudo pacman -Syu mpv anki curl xclip --needed
 
   If the command fails, find a compatible build on the [mpv website](https://mpv.io/installation/)
   or instead install FFmpeg and [enable FFmpeg support](#configuration) in `mpvacious`'s config file.
-
-  Most problems with adding audio or images to Anki cards can be fixed by installing and enabling FFmpeg separately.
+* Most problems with adding audio or images to Anki cards can be fixed
+  by installing FFmpeg and enabling it settings.
 
 ## Installation
 

howto/flatpak.md

@@ -0,0 +1,27 @@
+# Flatpak notes
+
+We think it's best to never use Flatpak.
+Specifically, try not to use Flatpak to install `mpv` and `anki`.
+Install packages from the official repositories of your distro or from the AUR.
+
+Read the following notes if you still decide to use Flatpak.
+
+Make these changes in Flatseal:
+
+* Enable "Filesystem > All system files"
+  so it could see `wl-copy`.
+  Unfortunately, there's no option to provide only a specific system file.
+* Add `~/.var/app/net.ankiweb.Anki` to "Filesystem > Other Files"
+  so mpvacious could add encoded snapshots and audio to Anki.
+* Add `PATH=/home/USERNAME/.local/bin:/home/USERNAME/bin:/app/bin:/usr/bin:/run/host/usr/bin` to "Environment > Variables".
+  There's no option to add a path to `PATH` in Flatseal,
+  so I opened container,
+  saved it's PATH and added `/run/host/usr/bin`
+  so mpvacuous could access `wl-copy`.
+* Enable "Shared > Network".
+  It's enabled by default, but anyway.
+
+The mpv config root is `~/.var/app/io.mpv.Mpv/config/mpv`
+
+* `~/.var/app/io.mpv.Mpv/config/mpv/scripts`
+* `~/.var/app/io.mpv.Mpv/config/mpv/script-opts`